arXiv subjects

Marina Eckermann

Publications and source records attributed to Marina Eckermann.

2 recordsLinked to original sources

arXiv2026

Amplitude-based echo-mode speed-of-sound tomography

The tissue's speed of sound (SoS) is a promising marker for non-invasive and zero-dose diagnosis of diseases such as cancer or liver steatosis. Computed ultrasound tomography in echo mode (CUTE) retrieves spatially resolved SoS using pulse-echo ultrasound, by analysing the variation of echoes when probed with varying pairs of transmit- and receive-steering angles. This analysis conventionally focuses on the echo phase shift, which is interpreted as differential time-of-flight (dToF) and related to SoS. While promising results have been obtained, the trade-off between beamwidth and angular aperture not only limits spatial resolution but also leads to artefactual noise in media with short-scale SoS variations. To overcome this limitation, we propose an alternative approach: for each echo, instead of reducing the angle-dependent variations to a single parameter (the dToF), we retrieve aberration profiles with sub-beamwidth resolution by inverting a model that relates these profiles to the echo amplitudes detected for all angle pairs. We demonstrate in simulations that this amplitude-based (a-CUTE) approach results in substantially improved spatial resolution and reduced artifacts compared to dToF-CUTE. Physical phantom and preliminary in vivo results confirm the feasibility of this novel method in physical data.

physics.med-ph↗

arXiv2025

Near-perfect efficiency in X-ray phase microtomography

X-ray microtomography at synchrotron sources is fundamentally limited by the high radiation dose applied to the samples, which restricts investigations to non-native tissue states and thereby compromises the biological relevance of the resulting data. The limitation stems from inefficient indirect detection schemes that require prolonged exposures. Efforts to extract additional contrast through multimodal techniques, like modulation-based imaging, worsen the problem by requiring multiple tomographic scans. In addition, the techniques suffer from low modulator pattern visibility, which reduces measurement efficiency and sensitivity. We address both the detection efficiency and modulation visibility challenges using a novel setup that combines an X-ray waveguide, a structured phase modulator, and a photon-counting detector. Our approach simultaneously achieves near-theoretical limits in both visibility (95%) and quantum efficiency (98%), thereby enabling dose-efficient multimodal microtomography at single-micrometer resolution. This advance will enable new classes of experiments on native-state biological specimens with the potential to advance biomedical research, disease diagnostics, and our understanding of tissue structure in physiological environments.

physics.optics↗